The use of non-volatile digital storage has been a rapidly growing with the advancement of the computer market. The requirement for mobile non-volatile storage has been growing with the use of computer laptops. Furthermore with the requirement for larger capacities for music players such as the iPod player by apple (www.apple.com/ipod) the requirement for digital storage is ever growing. Devices such as digital cameras and mobile phones are using non-volatile memory cards such as the flash-cards by Sandisk (www.sandisk.com) to store images and other data. Other devices of the Key-Chain Storage family by M-systems (www.m-sys.com) include USB connectivity for computers to act as a floppy disk replacement.
A unit of digital storage such as a computer hard disk, a flash card or a Key-Chain storage device and other such digital storage devices will be referred herein as a digital media storage device, or a media device.
A media device, unlike a floppy diskette includes a controller with some RAM, and or ROM or other memory. This has become necessary as these devices became more complex, managing their media transparently to the appliance, for example, in order to hide media defects and manage the media on a higher level.
A media device includes a certain constant amount of storage capacity, and is managed as a single unit by the appliance using it. For example, a computer hard disk is a single storage entity. If more storage capacity is required, another hard-disk is added. This hard-disk is then considered as a different volume and receives another drive letter in the Windows operating system, or may be mounted within the directory tree of the existing hard-disk in a Unix operating system. In this case, a hard disk is a single unit of capacity meaning files cannot be homogeneously stored on both hard drives.
A media device such as a USB key-chain storage device has got a constant amount of storage similar to a hard disk. This capacity is constant. It is formatted and it is then a single storage entity, which may be connected to a Windows or a Unix system like the case in adding a hard disk.
The term digital appliance will be referring to appliances such as a multimedia player, a camera, a mobile phone, a PC and so forth. The digital appliance may include some internal unit of storage capacity, and may include an expansion slot for adding more storage capacity. The additional storage capacity available in the case of digital appliances is similar to adding another volume in a computer. The storage available is then viewed as two different storage volumes. This limits the user by not being able to store a file larger than the maximum size of the different volumes. Furthermore, the user has to be aware of these different volumes and manage them.
A user owning a media device with storage capacity X who would like to own a single media device with storage capacity X+Y, has to purchase a new media device with storage capacity X+Y. It is not possible to expand an existing media device of capacity X with another media device of capacity Y to form a single larger capacity media.
This limitation of not being able to expand media device capacity is due to hardware and software reasons. On the hardware side, it is always easier to design a single unit that does not require expansion. On the software side, an operating system format such as FAT32, NTFS etc, is a static format in the sense that the storage capacity of the media device does not change. If the size of the capacity would somehow change, reformatting of the device is required to incorporate the new capacity size, leading to the erasing of the entire media device contents.
A user owning a media device having a certain capacity cannot expand the capacity of that device. Instead the user has to purchase a new media device in order to get a larger media device. For digital appliances such as a multimedia players or any other appliance that including non-volatile storage, the case for capacity expansion is similar to the media device problem. The device may have an expansion slot for including another storage volume, in which case an existing expansion card has to be replaced. If there is no expansion slot available, the appliance has to be replaced to increase its capacity size.
Although for key-chain USB devices it is possible to carry several media devices and use them all, this is not practical since the need for larger files is growing and having to split large files between different devices is cumbersome and not practical. Using several devices is altogether not practical and cumbersome.
It is therefore a disadvantage that media devices as well as digital appliances have to be replaced when increased capacity is desired. There is thus a widely recognized need for a media device that can be dynamically expanded to keep existing data valid through device capacity expansion, and it would be highly advantageous to have such a device devoid of the above limitations